Drilling fluids containing synthetic resinous materials



DRILLING FLUIDS CONTAINING SYNTHETIC RESINOUS MATERIALS Russell L. Sperry, Ojai, Calif. Keystone Labs End, 340 E. Santa Clara St., Ventura, Calif.)

No Drawing. Filed Jan. 29, 1959, Ser. No. 789,776

8 Claims. (Cl. 252--i.5)

This invention relates to the production of synthetic chemical compounds from organic materials and their use in drilling muds to improve their properties. This application is a continuation-in-part of my earlier application Serial No. 574,992, filed March 30, 1956, now U. S. Patent No. 2,894,940, and entitled Production of Synthetic Resinous Materials by Acid Charring of Lignins.

One object of the invention is to provide new and effective reagents for conditioning well-drilling liquid muds, more specifically clay-water base drilling fluids.

Another object of this invention is to produce high molecular-weight polycarboxylic acid compounds from lignins, and to use acids produced therefrom, and alkali salts of such acids, in oil-well drilling muds for reducing water-loss during drilling, for reducing'the viscosity of the muds, and for emulsifying oil therein.

A further object of the invention is to convert lignins, by acid dehydration or charring of the indicated raw materials, to black resin-like materials of relatively inert nature, it being also an object to convert such resin-like products by fusion with or digestion in water solutions of strong alkalis (more particularly the Group I alkali metal hydroxides) at high temperature to form the watersoluble alkali metal salts of corresponding acidic derivatives of the resin-like materials, it being also an object of the invention to prepare the free acids from the indicated salts, as by acidizing solutions of the salts, accompanied with the recovery of the acids, which are precipitated.

It is to be understood that the term lignin is used to include those organic materials known as lignins, lignosulfonic acids, and salts and derivatives thereof, as well as the various types of lignin materials produced as side products by the pulp and paper industry.

When wood chips are subjected to the action of the pulping liquor, the lignin present in the wood is largely dissolved, thereby freeing the fibrous cellulose. When the pulping liquor is alkaline, the lignin subsequently recovered from the liquor is known as alkali lignin. This serves to dilferentiate it from the lignin sulfonic acids and lignosulfonates which are recovered from the pulping of wood by the most common acid process, the sultite process. The lignosulfonates are sometimes recovered as the alkali salts, particularly mixed calcium salts. The Indulins produced by the West Virginia Pulp and Paper Company are representative of the alkali lignins. The Marasperses produced by the Marathon Corporation are examples of the lignosulfonates.

l have discovered that such lignins may be charred" with strong mineral acids, more particularly sulfuric acid (including sulfur trioxide) and hydrochloric acid, preferably sulfuric acid, under controlled conditions to yield a black, resin-like, almost inert material, which, however, is largely made up of a product soluble in alkali metal hydroxide solutions at high temperature only, that is, in the neighborhood of 450 F. or above, e.g. up to 550 F. or 600 F. Whereas the acid-catalyzed destructive 2,976,235 Patented Mar. 21, 1961 distillation of lignins to a variety of organic compounds is well known, this invention relates to the almost quantitative conversion of the lignins, including the lignin sulfonic acids and lignosulfonates, to an intermediate black resin-like dehydration product, which in turn can be converted almost quantitatively to the alkali metal salts of black, high-molecular-weight polycarboxylic acids by fusion with, or digestion in water with, the Group I alkali-metal hydroxides at temperatures above about 450 R, such as 500 F. to 600 F. Although concentrated acids, such as fuming or 98% H 30 are good for charn'ng, concentrations down to 50%, 20%, and even lower, e.g. 5%, in the case of H are usable, it being, however, necessary that there be suflicient acid to char the quantity of the organic portion of the lignin being treated. Whereas reaction with excess 80% or stronger sulfuric acid may be completed within a few minutes, charring with dilute acid may require several hours at around F. to 200 F.

With reference to the charring of the lignins according to the present invention, the term charring and the corresponding term char or char-resin signify the production of a black resin-like product by the respective strong acid employed, the treatment, however, not being carried to yield a largely free-carbon product but to yield a resinous reaction product, or dehydration product, which product is reactable with Group I alkali metal hydroxides (such as sodium hydroxide) to yield the described black alkali metal salts which are soluble in water and from which solution the described black, highmolecular-weight organic acids are precipitated upon acidification.

The indicated char resins are producible from the lignins by reaction with sulfuric acid under varyng conditions of temperature and ratio of sulfuric acid to the organic lignin or the organic portion of the lignin, if a salt, within a range between about 150 F. and about 350 F. and ratios of about 02 part of acid to a large excess of acid to one part of lignin. Whereas resin char may be formed almost instantly (vigorous exotherm) on reacting lignins with excess 80% or stronger sulfuric acid at about F. or above, practical application allows wide apparent variations of conditions. Where the temperature of reaction is in the lower range (about 150 F. to F.) and the ratio of sulfuric acid to lignin (organic content basis) is about 0.3 to 1 to 0.6 to 1, the time of reaction may be continued for many hours, such as 16 to 24 hours, without materially lowering the yield of desired product. However, as the ratio of acid to lignin is increased and/or the temperature is increased up to about 350 F., the time periods of heating are desirably decreased correspondingly, since otherwise the resin desired is slowly converted to carbonaceous materials which are not soluble in caustic solutions even at 500 F.

The use of dilute sulfuric acid is very advantageous, particularly when the raw materials are insoluble or only slowly soluble in acid solutions, since it allows uniform distribution of a low ratio of acid throughout the lignin. Under these conditions evaporation of water to yield about 80% or stronger sulfuric acid and subsequent charring of the lignin takes place smoothly without uncontrollable exothermic reaction. The speed of the conversion can be regulated both by the actual temperature and the rate of removal of water vapor from the zone of reaction.

Such procedures thus produce the required char resins which are reactable with Group I alkali metal hydroxides at the indicated high temperatures (about 450 F. to 600 F.) to yield the indicated black alkali metal salts from which the black high-molecular-weight water-insoluble organic acids may be obtained by precipitation from water solution upon acidification. In reacting the char with alkali, the ratio of alkali metal hydroxide to char ranges between about 0.2 to l to about 1.3 to 1 on a dryweight basis. AIi-alyses and properties of the chars and acids derived from the various lignins indicate a striking resemblance to those derived by the same proce ss from carbohydrates (according to my patent application Ser. No. 558,620, now US. Patent No. 2,881,211). Infra-red analyses indicate that the acids derived-from the lignins contain phenolic groups in addition to the carboxyl and hydroxyl groups present in the acids derived from the carbohydrates. Since some investigators report the presence of glucose andhydroxy methyl furfural among lignin decomposition products, the described reaction of the lignins may be reactions of modified carbohydrate groupings in the lignin molecule although investigators seem to agree that lignins do not contain carbohydrate groupings as such. The structure of lignins has not been definitely established. a

PROCEDURE.

The procedure as a Whole involved in this improvement involves the several steps which principally include the following:

Step I; The lignin is charred with acid, preferably sulfuric acid or acceptably strong hydrochloric acid, under appropriate conditions.

Step II: The char may be crushed and Washed with water to remove and recover residual acid.

Step III: The char, wet or dry, is mixed mm a Group I alkali metal hydroxide such as sodium hydroxide, both the char and hydroxide being preferably powdered or crushed, or such powdered or crushed char is slurried in a water solution of alkali hydroxide. By fusion of the char and hydroxide mixture (wet or dry) at a temperature of about 450 F. or above, such as 550 F. to 600 F.; or by digestion of the water slurry of the reactants in a pressure reactor at about 450 F. or above, such as up to 600 F., the char is converted to black water-soluble salts of high-molecular-weight organic acids. Such salts may be recovered from an aqueous solution as by evaporating to obtain substantially pure salts containing perhaps residual alkali metal hydroxide and carbonates.

Step IV: Water solution of the sodium salts formed as above is acidified with mineral acid such as hydrochloric or sulfuric acids, or weak organic acids such as acetic acid, whereupon the high-molecular-weight synthetic acids, produced by the ch'arring and the high tem-" perature reaction with alkali, are precipitated at about 7 or lower pH. The acids are then isolated and washed with water to remove soluble materials.

When properly prepared from the commercial lignins and lignosulfon'ates, the washed and dried char requires a minimum of about by weight of sodium hydroxide (or equivalent KOH or LiOH) based on the weight of the char to effect complete conversion of the char to the corresponding salts of the high-molecular-weight acids. The highest over-all conversion of the lignin to the corresponding black high-molecular-weight acids of step IV has been 88% based on the organic portion of the starting material. The char when properly prepared is insoluble or only slightly soluble in all the common solvents tested, and in 50% sodium hydroxide solution even up to 350 F., but does react with and become soluble in a water solution of sodium hydroxide at about 450 F. or above, as indicated above. Even at 450 F., the reaction is relatively'slow and often requires an hour or more to go to completion. At about 500 F. or above, however, the reaction appears almost instantaneous (even With 5% to NaOH solutions) since complete solubility has been obtained in five minutes at 500 F.

Specific procedures under the various steps I through IV, as indicated above, are included in the following r 4 Y examples which are summarized in table form to be more readily understood:

Group I.Preparation of resin-chars and high-molecularweight acids therefrom using low temperatures and low ratios of acid to lignin in step I The yields of resin and acids derived from the indicated lignin given in Table I were obtained by the following procedure: The lignin was uniformly wetted with 1% times its weight of 43% by weight sulfuric acid, giving a variable ratio of H 80 to the organic portion of the lignin (about 0.8 to -1 for 'Indulin A up to about 1:1 for Marasperse C). The treated lignin was then heated in an oven at 180 F. for 24 hours. The resultant char was crushed and slurried in water, filtered, washed thoroughly with boiling water, and dried at 125 C. The char was then slurried in about 4 times its weight of water containing 60% NaOH based on the weight of the char. The slurry was heated in a pressure reactor for 15 minutes at 490 F. to 520 F. The resulting black solution was filteredto remove traces of insolubles. The filtrate was diluted and acidified with hydrochloric acid. The resultant flocculated acids were recovered by filtration and thoroughly washed with water to remove residual salts and acid. The filtrates in all cases were colorless to very pale yellow in color. The recovered black acids were dried at 105 C.

The various Indulins and Marasperses of the above list are convenient examples of suitable lignins for the present method. The Indulins are produced by West Virginia Pulp and Paper Company of Charleston, South Carolina, and the various Marasperses are produced by the Marathon Corporation of Rothschild, Wisconsin. It is stated that Indulin A is a purified pine wood lignin derived from paper-pulp sulfate black liquor containing over 99.5% organic material; is a brown free-flowing amorphous powder, insoluble in water and acids, and soluble in alkali solutions; and normally has a pH running between 3.0 and 4.5. Indulin B is a purified sodium salt of pine wood lignin, containing about 4.0% sodium, which lignin is separated from paper-pulp sulfate black liquor; is soluble in water and alkali but insoluble in acids; and has a pH range from 8 to 9. Indulin C is a crude sodium salt of pine wood lignin, containing about 10% sodium, which lignin is separated from paper-pulp sulfate black liquor; is a brown free-flowing amorphous powder containing some occluded black liquor; and has a pH range from 9 to 10. The listed Marasperses constitute a group of sodium and calcium lignin sulfonic acid compounds which are soluble in water, insoluble in oils and most inorganic solvents, and have a pH range from 7.0 to 9.0.

The Indulins and Marasperses above are merely specific representatives found on the market of various lignins, lignosulfonic acids, their salts and other derivatives thereof, included within the general term lignins of this application and usable for the present purpose.

Group II.Preparation of resin-chars and high-molecular-weight acids using excess concentrated acid and allowing a short time high-temperature exothermic action The'yields of resins and acids from the indicated lignins given in Table II were obtained by procedures identical to the above with the following exceptions:

(1) The lignin was slurried in about twice its weight of 96% sulfuric acid. The slurry blackened, expanded Oil may be added to either of the above muds to form oil-in-water emulsion fluids.

In order to show the valuable characteristics of the synthetic salts and acids of this invention, comparative in volume, varying amounts of S were evolved, and 5 tests with standard drilling mud reagents were run simulthe temperature rose exothermic-ally to above 200 F. taneously. Such reagents have been indicated in the In all cases reaction appeared complete in to following tables as:

minutes. (1) Cypan, which is a sodium polyacrylate marketed (2) The char was converted to black soluble salts by the American Cyanamid Co., and is a very active using 40% NaOI-I based on the weight of the char. in water-loss control reagent; it is a non-emulsifier by usual TABLE H standards.

(2) Quebracho, which is a tannin in general use in Percent f Percent all types of drilling fluids; also a non-emulsifier.

(3) Lignite, dried and ground, is used in large voli sa d cn Based on 15 ume as an emulsifier, particularly in higher pH (9 to fifif l3) muds and in lime muds.

All tests were run by adding the indicated number of mdulm A" 83 86 grams of reagent to 350 cc. of the prepared mud, these Induliu B 7s 90 amounts being the equivalent to the same number of fig gg 22 pounds per 42 gallon barrel of mud. Such treated mud Maraspcrse G B 07 82 in each test was then heated with agitation (rolls) in a msperseN 56 92 closed vessel at 160 F. to 170 F. for 16 to 24 hours.

The water-loss was run on the hot mud by the standard Group HIP-Preparation Sodium Salts f the black A.P.I. 100 lbs/sq. in. method, the water loss recorded, high-molecular'weight acids 25 as cc. of filtrate in 7.5, 15, and minutes. The viscosities Preparations using both general methods indicated in Pmsent Purposes are recorded as thlck, medium: Groups I and 11 above were carried only to the sodium salt stage. The solutions of the black salts were evapotests are Presented Senes K the Pamcular rated to dryness at 105 C. for testing in drilling muds. (heated muds a blank 9 and tests Wlth the weu'knoljvn The yields of water-soluble salts ranged between 92% 30 control reagents f ig g ven first, followed by tests with and 100% based on the total Weight of the Chan-68in the products of this nvention der1ved from the lndicated and Group I alkali metal hydroxide lignins. The free acids, designated by X in these tables, were prepared according to Group I or II methods above, DRILLING MUD TREATMENT and were predissolved in caustic solution as indicated. The use of the synthetic acids and their sodium salts Where the Products of This invfimion are designated as of this invention for treating drilling muds will be under- NaX, the Was P p according t0 GYOHP 111 above, stood by those skilled in the art from the results supplied andcontalned y Soluble impurities fomled in the P l by the following examples. Such high-molecular-weight f l Comparison also, tests Wlth three of the synthetic products are shown to be efiective in various hgnlns, from whlch the p d s of t i invention w types of clay-water-base muds and oil-in-water emulsion P F included 1116 611d 0 ri I a d I muds as commonly used by the oil industry. For test- USE OF SALTS AND ACIDS 1N DRILLING MUDS ing purposes two basic types of clay-base muds have been Series No 1 employed:

(1) Low PH to 10) gypsum, Sa1t comaminated Commercial P- clay was hydrated 24 hours with mud made up by hydrating a good commercial bentonite 45 gypsflm Saturated ater containing about g.p.g. clay in gypsum-saturated, salt-contaminated water. (grams Per gallon) NacL The adlusted to (2) High pH (1043) lime mud prepared by adding 04 lbs/cu. ft. Each reagent or combination of reagents lime and caustic to any clay-base drilling mud along with lndlcated was Predlssolved In 10 Water, which Was lignite, quebracho, or other similar reagent, in amount also added to the blank mud. The samples were heated suflicient to maintain suitable viscosity, gel, and Water- 50 at F. to F. with agitation for 20 hours as indiioss characteristics. Caled above and testedcc. Water Loss- A.P.I., minutes Test No. Gm. Reagent Acids Source Viscosity pH 1 21.4 29.8 Thick. 8.2 2 f 10.5 14.0 Thin 10.7 3 18.3 25.8 Medium- 10.3 i 5.2 7.8 Thick... 8.4 f 5.8 8.0 Thin 10.1 2 0.0 9.0 do 10.2 0.5 9.2 mac 10.0 f 7.5 10.8 Medium... 10.2 f 5.8 7.9 Thin 10.0 3 5.0 7.0 do 9.0 f 8.0 11.1 -do 0.9 a 0.7 9.9 Medium... 10.1 NaoH 16.8 24.3 Thick 0.7 gg gff ..do 12.4 17.8 25.0 do 0.7 Mamfferse 10.8 24.0 9.0

In addition to the value of the prepared acids and alkali salts thereof for controlling the viscosity and wateriloss they; also have, excellent emulsifying; properties. The 15 samples of mud above were recovered, including the filtrates and Wall cakes which were redispersed in each instance; 10% by' volume (35 cc.) of 32. gravity Ventura crude oil was added to each sample; the samples were reheated with mild agitation at 160.F. to 170 F. for four to five hours; and the samples again tested for water loss and the presence of free oil with the following results: 7

10 way. "Obviously, the use of the sodium salts recovered directly from the fusion step would aiiord the lowest F cost product. 00. Water Loss- I h All minutes 30 mm Water In any case, sn ce the pH of the mud is generally above Results lossabovabefore about 7.5, the ac1ds are present 1n the mud 1n salt form, 7 5 15 30 adding 011 15 and the activity is then effectually a measure of the activity of the soluble salts formed in the mud. 1A EceSSfme on 1&0 1&8 2&6 (29.8) Especlally from the following series of tests, it w1ll 2AExcess free 11.-.. 7.3 10.0 13.2 14.0) be noted that the greater the proportlon of-the g1ven 011m (25-8) acid or its alkali metal salt employed, the lower is the 4A-Exccss free 01.1-... 5.2 4.0 7.2 (7.8) 511:Someireeoil 1 3.0 4.4 3.2 3.63 20 water-loss. Tins is especially true in the range of about 6 Some free oi. 3.3 5.0 .0 .0 1 7A som free 011 a 4 4 18 (Q2) A lb. per barrel to 6 lbs. per barrel of salt in the mud SA-Tracefrce oil. 4.0 5.9 8.3 (10.8) and contlnues up to about 10 lbs. per barrel in laborafi iigg ggsg 38 :3 g; tory muds. As is well known to those trained in the llA-Tracofree o 1l 5.0 2.3 10.2 (11.1) art, the concentration of a reagent required to produce EQISZEZ i5 1% 2: 25 a desired efieot on a field mudwill vary extremely with 14As men-Qe 011-- 9.2 14.4 21.2 2 5.0) the type of mud and the parucular effect desired. As A" 132 much as lbs. of these reagents per barrel of mud Series No. 2

The potential value of these products V for treating lime muds is indicated by the following test results. A

sample of lime mud from a well in Ventura, California,.

of Tidewater Associated Oil Co. was diluted with 10% of its volume with water. Samples were treated with the indicated reagents, heated with agitation as above for 16 hours and tested as above. The sodium salts of the acids of this invention were obtained by drying the solution obtained by digesting the indicated chars with might prove advantageous to emulsify 20%, 30%, or oil in the mud, to overcome extreme salt or gypsum contamination, or in preparing lime muds of extreme lime concentration. Therefore, the effectiveness of a reagent can be proved by laboratory tests, but an upper limit of practical concentration cannot be established by the effect on any one mud.

Series No. 3

Tests run as usual (above) on 84 lbs/cu. ft. P- hydrated in hard water.

40% by weight NaOH (according to Group III above) Thus, it is apparent that there has been provided 00. Water Loss- 1 A.P.I., minutes 7 Test N 0. Gm. Reagent Salts Source V1scoslty pH a Blank 3.8 5. 4 7. 8 Medium-.- 12. 2 Qlmmcho" o 2.7 as 5.7 fvmthin. 13=1= CommerciaL NaOH do 2.9 4. 1 6.1 T1111 1 13d: NaX Marasperse C-.. 1. 7 2.8 4.2 do 12.0 NaX Indulin A 2. 5 3. 6 5. 2' do 12.1

The abovemud was in use while drilling at about 7() novel drilling fluids which fulfill all of the objects and 11,000 feet depth. Previous treatment had consisted... advantages sought therefor.

essentially of caustic, lignite, quebracho, lime andcrude It is to be understood that the foregoing description oil; small'amounts of Driscose (carboxymethyl cellulose) and examples were given only by way of illustration, and had also .beenused. 1 i that. changes and alterations in the present disclosure It is n rsm .trczuthe. abqyeresul s. .t tatlh l t e' {51.11.1 101W111b2 readi y app to one skilled in the art 9 are contemplated as within the scope of the present inv'filgiiill which is limited only by the claims which follow.

arm:

1. A well-drilling fluid comprising: water; clayey solids; and alkali metal salts produced by charring lignin materials to char resins with an acid selected from the group consisting of sulfuric acid, sulfur trioxide, and hydrochloric acid at temperatures between from about 150 F. to about 350 F. to yield a char substantially insoluble in alkali metal hydroxide below 350 F., and reacting the resultant char resins with alkali metal hydroxides at temperatures between from about 450 F. to about 600 F. to produce water-soluble alkali metal salts of high-molecular-weight organic acids, the metal salts being in the proportion of about one-fourth pound to about twenty pounds per forty-two-gallon barrel of fluid.

2. An :oil-in-water type well-drilling emulsion comprising: water; clayey solids; oil; and alkali metal salts produced by charring lignin materials to char resins with an acid selected from the group consisting of sulfuric acid, sulfur trioxide, and hydrochloric acid at temperatures between from about 150 F. to about 350 F. to yield a char substantially insoluble in alkali metal hydroxide below 350 F., and reacting the resultant char resins with alkali metal hydroxides at temperatures between from about 450 F. to about 600 F. to produce water-soluble alkali metal salts of high-molecular-weight organic acids, the metal salts being in the proportion of about one-fourth pound to about twenty pounds per forty-two-gallon barrel of emulsion.

3. A well-drilling fluid comprising: water; clayey solids; and alkali metal salts produced by charring lignin materials to char resins with an acid selected from the group consisting of sulfuric acid, sulfur trioxide, and hydrochloric acid at temperatures between from about 150 F. to about 350 F. to yield a char substantially insoluble in alkali metal hydroxide below .350" F., the ratio of acid to the organic portion of the lignin material on a dry basis being in the range of from about 0.3:1 to about :1,. and reacting the resultant char resins with alkali metal hydroxides at temperature between from about 450 F. to about 600 F. to produce water-soluble alkali metal salts of high-molecular-weight organic acids, the ratio of alkali metal hydroxide to char resin on a dry basis being in the range from about 0.2:] to about 1:1, the metal salts being in the proportion of about onefourth pound to about twenty pounds per forty twogallon barrel of fluid.

4. An oil-in-water type well-drilling emulsion comprising: water; clayey solids; oil; and alkali metal salts produced by charring lignin materials to char rmins with an acid selected from the group consisting of sulfuric acid, sulfur trioxide, and hydrochloric acid at temperatures between from about 150 F. to about 350 F. to yield a char substantially insoluble in alkali metal hydroxide below 350 F., the ratio of acid to the organic portion of the lignin material on a dry basis being in the range of from about 0.311 to about 1.5: 1, and reacting the resultant char resins with alkali metal hydroxides at temperatures between from about 450 F. to about 600 F. to produce water-soluble alkali metal salts of high-molecular-weight organic acids, the ratio of alkali metal hydroxide to char resin on a dry basis being in the range from about 0.2:1 to about 1:1, the metal salts being in the proportion of about one-fourth pound to about twenty pounds per fonty-two-gallon barrel of emulsion.

5. A well-drilling fluid comprising: water; clayey solids; and synthetic organic acids produced by charring lignin materials to char resins with an acid selected from the group consisting of sulfuric acid, sulfur trioxide, and bydrochloric acid at temperatures between about 150 F. and about 350 F. to yield a char substantially insoluble in alkali metal hydroxide below 350 F., reacting the resultant char resin with alkali metal hydroxides at temperatures between about 450 F. and about 600 F. to produce watersoluble alkali metal salts of high-molecular-weight organic acids, acidizing a water solution of the alkali metal salts to precipitate the high-molecularweight acid constituents, and recovering the precipitated acids, the acids being in the proportion of about onefourth pound to about twenty pounds per forty-two-gallon barrel of fluid.

6. An oil-in-water type well-drilling emulsion comprising: water; clayey solids; oil; and synthetic organic acids produced by charring lignin materials to char resins with an acid selected from the group consisting of sulfuric acid, sulfur trioxide, and hydrochloric acid at temperatures between about F. and about 350 F. to yield a char substantially insoluble in alkali metal hydroxide below 350 F., reacting the resultant char resin with alkali metal hydroxides at temperatures between about 450 F. and about 600 F. to produce water-soluble alkali metal salts of high-molecular-weight organic acids, acidizing a water solution of the alkali metal salts to precipitate the high-molecular-weight acid constituents, and recovering the precipitated acids, the acids being in the proportion of about one-fourth pound to about twenty pounds per forty-two-gallon barrel of emulsion.

7. A well-drilling fluid comprising: water; clayey solids; and synthetic organic acids produced by charring lignin materials to char resins with an acid selected from the group consisting of sulfuric acid, sulfur trioxide, and hydrochloric acid at temperatures between about 150 F. and about 350 F. to yield a char substantially insoluble in alkali metal hydroxide below 350 F., the ratio of acid to the organic portion of the lignin material on a dry basis being in the range of from about 0.3:1 to about 1.5: 1, reacting the resultant char resins with alkali metal hydroxides at temperatures between about 450 F. and about 600 F. to produce water-soluble alkali metal salts of high-molecular-weight organic acids, the ratio of alkali metal hydroxide to char resins on a dry basis being in the range from about 0.2:1 to about 1:1, acidizing a Water solution of the alkali metal salts to precipitate the high-molecular-weight acid constituents, and recovering the precipitated acids, the acids being in the proportion of about one-fourth pound to about twenty pounds per forty-two-gallon barrel of fluid.

8. An oil-in-water type well-drilling emulsion comprising: water; clayey solids; oil; and synthetic organic acids produced by charring lignin materials to char resins with an acid selected from the group consisting of sulfuric acid, sulfur trioxide, and hydrochloric acid at temperatures between about 150 F. and about 350 F. to yield a char substantially insoluble in alkali metal hydroxide below 350 F., the ratio of acid to the organic portion of the lignin material on a dry basis being in the range of from about 0.3:1 to about 1.5 :1, reacting the resultant char resins with alkali metal hydroxides at temperatures between about 450 F. and about 600 F. to produce watersoluble alkali metal salts of high-molecular-weight organic acids, the ratio of alkali metal hydroxide to char resins on a dry basis being in the range from about 0.2:1 to about 1:1, acidizing a water solution of the alkali metal salts to precipitate the-high-molecular-weight acid constituents, and recovering the precipitated acids, the acids being in the proportion of about one-fourth pound to about twenty pounds per forty-two-gallon barrel of emulsion.

References Cited in the file of this patent UNITED STATES PATENTS 1,999,766 Lawton et al. Apr. 30, 1935 2,491,436 Barnes Dec. 13, 1949 2,552,775 Fischer May 15, 1951 2,798,043 Meister et al July 2, 1957 2,894,940 Sperry July 14, 1959 

1. A WELL-DRILLING FLUID COMPRISING: WATER; CLAYEY SOLIDS; AND ALKALI METAL SALTS PRODUCED BY CHARRING LIGNIN MATERIALS TO CHAR RESINS WITH AN ACID SELECTED FROM THE GROUP CONSITING OF SULFURIC ACID, SULFUR TRIOXIDE, AND HYDROCHLORIC ACID AT TEMPERATURES BETWEEN FROM ABOUT 150*F. TO ABOUT 350*F. TO YIELD A CHAR SUBSTANTIALLY INSOLUBLE IN ALKALI METAL HYDROXIDE BELOW 350*F., AND REACTING THE RESULTNAT CHAR RESINS WITH ALKALI METAL HYDROXIDES AT TEMPERATURES BETWEEN FROM ABOUT 450*F. TO ABOUT 600*F. TO PRODUCE WATER-SOLUBLE ALKALI METALS SALTS OF HIGH-MOLECULAR-WEIGHT ORGANIC ACIDS, THE METAL SALTS BEING IN THE PROPORTION OF ABOUT ONE-FOURTH POUND TO ABOUT TWENTY POUNDS PER FORTY-TWO-GALLON BARREL OF FLUID. 